Ultraviolet (UV) light represents the frequency of light between 185 nanometers (nm) and 400 nm, and it is invisible to the naked eye. There are three distinct bands of light within the UV spectrum: UV-A, UV-B, and UV-C. Longwave UV light (315 nm to 400 nm) or UV-A refers to what is commonly called “black light.” UV-B (280 nm to 315 nm) or midrange UV is the type of light that causes sunburn. Germicidal UV light (185 nm to 280 nm) or UV-C is effective in microbial control. For example, research has demonstrated that UV light between 254 nm and 265 nm can be very efficient in the destruction of various microbials and other microorganisms.
A photocatalytic air purifier is based on photocatalytic oxidation (PCO), a technology that converts fine particles and/or toxic gasses into safer compounds. Generally speaking, a photocatalytic air cleaner may use broad-spectrum, ultraviolet light, which reacts with a chemical catalyst (e.g., thin-film titanium dioxide-based material) to oxidize organic compounds, thus reducing or eliminating certain microorganisms otherwise present in the air.